Encourage client to not give up - this is not a failure, but a setback- boost motivation.
Important to distinguish between having an odd cigarette (lapse) compared to retreating back into normal smoking habits (relapse) and implications of each for continuation of the programme.
Becoming tobacco-free is an ongoing process and can take several quit attempts.
Learn from this setback and enforce coping strategies which could help resist the urge next time- what went wrong this time? What was the trigger?